This article originally appeared as a Design and Usability Tactics e-newsletter.
By Michael Meadhra
The Web-safe color palette contains the
colors that are supposed to render consistently across platforms
and browsers. But is this venerable tool an anachronism–a relic
from a bygone age that is no longer relevant in a time when most
computers are capable of displaying thousands or even millions of
colors?
Where did the Web-safe palette come from?
The Web-safe palette dates from the early days
of the Web when most computers could display only 256 colors. In
contrast, Web color codes specify 256 levels each of red, green,
and blue, producing 16.7 million possible colors. To reconcile the
difference, browsers must shift any color that doesn’t match one of
the available display colors to the nearest 256-color equivalent or
use dithering to simulate the specified color.
Dithering and shifting colors are, of course,
highly undesirable characteristics for Web objects. The color
shifts are often unpredictable and may even cause objects to
disappear if the foreground and background shift to the same color;
hence the need to identify colors that don’t exhibit those problems
on a 256-color display.
Netscape and Internet Explorer share 216 such
colors, which became known as the Web-safe color palette. The 216
colors are the result of arranging RGB values in a 6x6x6 matrix,
with black, white, and the primaries on the corners and colors
changing in 20-percent increments. (Reserved system colors for Mac
and Windows account for the other 40 colors.)
Problems with the palette
The Web-safe palette isn’t ideal. Although the
color increments are mathematically precise, it contains numerous
colors that are visually close to being duplicates, while some
color gradations seem to be missing steps. The palette is also
short on pastels, neutrals, and earth tones. As a result, designers
often can’t find the colors they want in the Web-safe palette, and
converting the desired colors to the nearest Web-safe match may not
produce satisfactory results.
Modern graphics cards and monitors are no
longer restricted to displaying 256 colors. In fact, almost all
recent computers can display thousands of colors (High Color) or
millions of colors (True Color). Statistics at TheCounter.com show
only 3 percent of site visitors use 256-color displays, compared to
40 percent for High Color and 55 percent for True Color.
High Color (16-bit) displays can’t reproduce
all the colors defined by Web color codes. Browsers deal with this
by mapping the color of each object to its closest High Color
equivalent. There’s a lot of color shifting going on, but with
thousands of colors to work with, the color shifts are generally
very subtle. High Color displays present their own problems to Web
builders, but the Web-safe palette doesn’t address those problems
directly.
True Color (24-bit and 32-bit) displays can
show all 16.7 million colors that you can define with Web color
codes. So there are no dithering or arbitrary color shift problems
when viewing a Web page on a computer with a True Color
display.
So why use it?
With the 256-color display for which it was
designed gradually disappearing, has the Web-safe palette outlived
its usefulness to Web builders? Surprisingly, I think not.
First, even the small percentage of Web
visitors using 256-color displays can translate to a significant
number of real page views at a popular site. When the site goals
include being accessible to the largest possible audience, the
Web-safe palette is a valuable tool for providing
display-challenged visitors with a predictable Web experience.
Perhaps a more important consideration is that
the High Color and True Color palettes are just too large to work
with effectively as you design a site. Designers need to carefully
test and become familiar with a smaller subset of the available
colors so they can predict how those colors appear on different
monitors and platforms. For now, the Web-safe palette fills that
need for most designers. Although some may supplement it with their
client’s corporate colors and other favorite shades, the Web-safe
palette serves as a common foundation for all Web builders.
Another palette that addresses some of its
aesthetic deficiencies will probably replace the Web-safe palette.
Until then, the Web-safe palette provides the traditional starting
point for most Web color schemes.
Michael Meadhra has been working in the IT field since the earliest days
of the Web. His book credits span some three dozen titles, including
How to Do Everything with Dreamweaver MX.
